Endovascular graft

ABSTRACT

An endovascular graft which is configured to conform to the morphology of the vessel to be treated and which is made from an inflatable structure having a proximal end with a proximal inflatable cuff and a distal end with a distal inflatable cuff. At least one elongated inflatable channel is disposed between and in fluid communication with fluid tight chambers of the inflatable cuffs which may contain rupture discs therebetween which can be configured to rupture at different pressures. A thin flexible barrier disposed between the inflatable cuffs and the elongated inflatable channel of the frame so as to form a tubular structure defining a longitudinal channel to confine a flow of blood or other fluid therethrough. The graft may also have an expansion member attached to the proximal end of the graft which is preferably made of linked expandable rings of pseudoelastic shape memory alloy which is self expanding and prevents axial displacement of the graft once it is deployed.

RELATED APPLICATIONS

[0001] This application is a continuation of Continued Prosecutionapplication Ser. No. 09/133,978, filed Aug. 14, 1998, which is acontinuation-in-part of Provisional Application No. 60/074,112, filedFeb. 9, 1998. The subject matter of each of the above patentapplications is incorporated by reference in its entirety herein.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a system and method for thetreatment of disorders of the vasculature. More specifically, a systemand method for treatment of abdominal aortic aneurysm and the like,which is a condition manifested by expansion and weakening of the aortabelow the diaphragm. Such conditions require intervention due to theseverity of the sequelae, which frequently is death. Prior methods oftreating aortic aneurysm have consisted of invasive surgical methodswith graft placement within the aorta as a reinforcing member of theartery. However, such a procedure requires a surgical cut down to accessthe vessel, which in turn can result in a catastrophic rupture of theaneurysm due to the decreased external pressure from the organs andtissues surrounding the aorta, which are moved during the procedure togain access to the vessel. Accordingly, surgical procedures have a highmortality rate due to the possibility of the rupture discussed above inaddition to other factors. Other factors can include poor physicalcondition of the patient due to blood loss, anuria, and low bloodpressure associated with the aortic abdominal aneurysm. An example of asurgical procedure is described in a book entitled Surgical Treatment ofAortic Aneurysms by Denton A. Cooley, M.D., published in 1986 by W.B.Saunders Company.

[0003] Due to the inherent risks and complexities of surgicalprocedures, various attempts have been made in the development ofalternative methods for deployment of grafts within aortic aneurysms.One such method is the non-invasive technique of percutaneous deliveryby a catheter-based system. Such a method is described in Lawrence, Jr.et al. in “Percutaneous endovascular graft: experimental evaluation”,Radiology (May 1987). Lawrence described therein the use of a Gianturcostent as disclosed in U.S. Pat. No. 4,580,568. The stent is used toposition a Dacron fabric graft within the vessel. The Dacron graft iscompressed within the catheter and then deployed within the vessel to betreated. A similar procedure has also been described by Mirich et al. in“Percutaneously placed endovascular grafts for aortic aneurysms:feasibility study,” Radiology (March 1989). Mirich describes therein aself-expanding metallic structure covered by a nylon fabric, with saidstructure being anchored by barbs at the proximal and distal ends.

[0004] One of the primary deficiencies of the existing percutaneousdevices and methods has been that the grafts and the delivery cathetersused to deliver the grafts are relatively large in profile, often up to24 French and greater, and stiff in bending. The large profile andbending stiffness makes delivery through the irregular and tortuousarteries of diseased vessels difficult and risky. In particular, theiliac arteries are often too narrow or irregular for the passage of apercutaneous device. Because of this, non-invasive percutaneous graftdelivery for treatment of aortic aneurysm is not available to manypatients who would benefit from it.

[0005] Another contraindication for current percutaneous graftingmethods and devices is a vessel treatment site with high neck angulationwhich precludes a proper fit between the graft and the vessel wall. Animproper fit or seal between the graft and the vessel wall can result inleaks or areas of high stress imposed upon the diseased vessel whichlead to reduced graft efficacy and possibly rupture of the aneurysm.

[0006] While the above methods have shown some promise with regard totreating abdominal aortic aneurysms with non-invasive methods, thereremains a need for an endovascular graft system which can be deployedpercutaneously in a small diameter flexible catheter system. Inaddition, there is a need for a graft which conforms more closely to thecontours of an aortic aneurysm which are often quite irregular andangulated and vary from patient to patient. The present inventionsatisfies these and other needs.

SUMMARY OF THE INVENTION

[0007] The present invention is directed generally to an endovasculargraft for vascular treatment and a method for manufacturing and usingthe graft. The graft generally has an inflatable tubular frame structurewhich can be configured to conform to the morphology of a patient'svessel to be treated. The frame structure has a proximal end and adistal end with an inflatable cuff disposed on at least one end andpreferably both. The inflatable cuffs can be reduced in diameter andprofile when deflated for introduction into a patient's vasculature by acatheter based delivery system or other suitable means. The inflatablecuffs provide a sufficiently rigid structure when inflated whichsupports the graft and seals the graft against the interior surface ofthe vessel in which it is being deployed. One or more elongatedinflatable channels may also be disposed on the graft. Preferably, theelongated channel is disposed between and in fluid communication with aproximal and distal inflatable cuff. The channel provides the desiredstiffness upon inflation, prevents kinking of the graft frame, andfacilitates deployment of the graft within a patient's body passageway.The elongated inflatable channel can be in a longitudinal or linearconfiguration with respect to the graft, but is preferably shaped as ahelix disposed about the graft. Other orientations such asinterconnecting grids or rings may also be suitable for the elongatedchannels. The inflatable cuffs and the elongated channel contain fluidtight chambers which are generally in fluid communication with eachother but which may also be separated by valves or rupture discs thereinto selectively control the sequence of inflation or deployment. Thefluid tight chambers are typically accessed by an injection port whichis configured to accept a pressurized source of gas, fluid, particles,gel or combination thereof and which is in fluid communication with atleast one of the fluid tight chambers. A fluid which sets, hardens orgels over time can also be used. The number of elongated channels canvary with the specific configuration of the graft as adapted to a givenindication, but generally, the number of channels ranges from 1 to 25,preferably 2 to about 8.

[0008] A proximal neck portion may be secured to the proximal inflatablecuff. The proximal neck portion has a flexible tubular structure thathas a diameter similar to the proximal inflatable cuff. The proximalneck portion can be configured as a straight tubular section or can betapered distally or proximally to an increased or decreased diameter.Preferably, the proximal neck portion is secured and sealed to theproximal inflatable cuff and tapers proximally to an increased diameterso as to engage the inside surface of a vessel wall which provides asealing function in addition to that of the proximal inflatable cuff.Such a configuration also smoothes the transition for fluid flow fromthe vessel of a patient to the lumen or channel within the endovasculargraft. The proximal neck portion has an inlet axis that preferably hasan angular bias with respect to a longitudinal axis of the graft.

[0009] Preferably, the graft has a monolithic structure wherein thematerial that comprises the inflatable cuffs and channels extendsbetween these elements in a thin flexible layer that defines alongitudinal lumen to confine a flow of blood or other fluidtherethrough. Such a monolithic structure can be made from a variety ofsuitable polymers including PVC, polyurethane, polyethylene andfluoropolymers such as TFE, PTFE and ePTFE. Additional stiffness orreinforcement can be added to the graft by the addition of metal orplastic inserts or battens to the graft, which can also facilitatepositioning and deployment of the graft prior to inflation of aninflatable portion of the graft.

[0010] In another embodiment, the graft has a thin flexible layerdisposed over or between a proximal inflatable cuff, a distal inflatablecuff, and an elongated inflatable channel of the frame. The thinflexible layer is made of a material differing from the material of thecuffs or elongated channel. The barrier is shaped so as to form atubular structure defining a longitudinal lumen or channel to confine aflow of blood therethrough. The flexible barrier may be made of avariety of suitable materials such as DACRON®, NYLON®, or fluoropolymerssuch as TEFLON® or the like.

[0011] An endovascular graft having features of the invention may bemade in a tubular configuration of a flexible layer material such asDacron, Nylon or fluoropolymers as discussed above. The inflatable cuffsand elongated channels are formed separately and bonded thereto. Theinflatable cuffs and channels may also be made from the same layermaterial, i.e., Dacron, Teflon, or Nylon with a fluid impermeablemembrane or bladder disposed within the cuff or channel so as to make itfluid tight. To limit permeability, the material in the regions of thecuffs and channels may also be treated with a coating or otherwise beprocessed by methods such as thermo-mechanical compaction.

[0012] In one embodiment of the invention, an expansion member isattached to the proximal end of the frame structure of the graft or to aproximal neck portion of the graft. Expansion members may also beattached to the distal end of the graft. Preferably, the expansionmember is made of an expandable ring or linked expandable rings ofpseudoelastic shape memory alloy which is self expanding and helps tomechanically anchor the proximal end of the graft to a body channel toprevent axial displacement of the graft once it is deployed. By havingan expansion member which is distinct from the proximal cuff, thesealing function of the cuff, which requires supple conformation to thevessel wall without excessive radial force, can be separated from theanchoring function of the expansion member, which can requiresignificant radial force. This allows each function to be optimizedwithout compromising the function of the other. It also allows theanchoring function which can require more radial force on the vesselwall to be located more proximal from the aneurysm than the cuff, andtherefor be positioned in a healthier portion of the vessel which isbetter able to withstand the radial force required for the anchoringfunction. In addition, the cuff and expansion members can be separatedspatially in a longitudinal direction with the graft in a collapsedstate for delivery which allows for a lower more flexible profile forpercutaneous delivery. Such a configuration makes a collapsed deliveryprofile of 12-16 French possible, preferably below 12 French.

[0013] The expandable ring or rings of the expansion member may beformed in a continuous loop having a serpentine or zig-zag pattern alonga circumference of the loop. Any other similar configuration could beused that would allow radial expansion of the ring. The expansion membermay be made of suitable high strength metals such as stainless steel,Nitinol or other shape memory alloys, or other suitable high strengthcomposites or polymers. The expansion member may be made from highmemory materials such as Nitinol or low memory materials such asstainless steel depending on the configuration of the endovasculargraft, the morphology of the deployment site, and the mode of deliveryand deployment of the graft.

[0014] The expansion member preferably has an inlet axis which forms aninlet axis angle in relation to a longitudinal axis of the graft. Theangled inlet axis allows the graft to better conform to the morphologyof a patient's vasculature in patients who have an angulated neckaneurysm morphology. The inlet axis angle can be from about 0 to about90 degrees, preferably about 20 degrees to about 30 degrees. Some or allof the inlet axis angle can be achieved in a proximal neck portion ofthe graft, to which the expansion member may be attached. An expansionmember or members may also be attached to the distal end of the graft.

[0015] In another embodiment of the invention, the graft may bebifurcated at the distal end of a main body portion of the graft andhave at least two bifurcated portions with longitudinal lumens in fluidcommunication with a longitudinal lumen of the main body portion. Thefirst bifurcated portion and second bifurcated portion can be formedfrom a structure similar to that of the main body portion with optionalinflatable cuffs at either the proximal or distal end. One or moreelongated channels can be disposed between the inflatable cuffs.

[0016] The size and angular orientation of the bifurcated portions canvary, however, they are generally configured to have an outer diameterthat is compatible with the inner diameter of a patient's iliacarteries. The bifurcated portions can also be adapted to use in apatient's renal arteries or other suitable indication. The distal endsof the bifurcated portions may also have expansion members attachedthereto in order to anchor or expand, or both anchor and expand saiddistal ends within the body passageway being treated. The expansionmembers for the distal ends of the bifurcated portions can have similarstructure to the expansion member attached to the proximal end orproximal neck portion of the main body portion. The expansion membersare preferably made from a shape memory material such as Nitinol.

[0017] In bifurcated embodiments of grafts having features of theinvention which also have a biased proximal end which forms an inletaxis angle, the direction of the bias or angulation can be importantwith regard to achieving a proper fit between the graft and themorphology of the deployment site. Generally, the angular bias of theproximal end of the graft, proximal neck portion or proximal expansionmember can be in any direction. Preferably, the angular bias is in adirection normal to a plane defined by a longitudinal axis of the mainbody portion, the first bifurcated portion and the second bifurcatedportion.

[0018] In another embodiment of the invention, rupture discs or othertemporary closures are placed between fluid tight chambers of theinflatable cuffs and elongated channel or channels of the graft and forma seal between the chambers. The rupture discs may be burst or broken ifsufficient force or pressure is exerted on one side of a disc ortemporary closure. Once the graft is located at the site to be treatedwithin a body passageway of a patient, a pressurized gas, fluid or gelmay be injected by an inflation catheter into one of the fluid tightchambers of the graft through an injection port. Injection of apressurized substance into an inflatable cuff will cause the cuff totake a generally annular shape, although the cuff can conform to theshape of the vessel within which it is deployed, and exert a sufficientradial force outward against the inner surface of the body passageway tobe treated in order to provide the desired sealing function.

[0019] Multiple rupture discs can be disposed in various locations ofthe graft and also be configured to rupture at different pressures orburst thresholds to facilitate deployment of the graft within a bodypassageway. In a particular bifurcated embodiment of the invention, theproximal inflatable cuff of the main body portion may be positionedproximal of a junction between the branch of the abdominal aorta and theiliac arteries of a patient. As the proximal cuff is deployed byinjection of an appropriate substance into an injection port in fluidcommunication with the fluid tight chamber thereof, it will expandradially and become axially and sealingly fixed proximal to thebifurcation of the aorta. A rupture disc is located between the fluidtight chamber of the proximal cuff and the elongated inflatable channelsso that the proximal cuff may be substantially deployed before therupture disc bursts and the elongated channels begin to fill with theinjected substance. The elongated channels then fill and becomesufficiently rigid and expand to create a longitudinal lumen therein. Aspressure is increased within the fluid tight chamber, a rupture discbetween the fluid tight chamber of the elongated channels and a fluidtight chamber of the optional distal inflatable cuff or distal manifoldof the main body portion will burst and the distal inflatable cuff ormanifold will deploy and become pressurized. One of the bifurcatedportions of the graft may then be deployed as a rupture disc sealing itsfluid tight chamber from the distal inflatable cuff or manifold of themain body portion of the graft bursts as the inflation pressure isincreased. Finally, the second bifurcated portion of the graft deploysafter a rupture disc sealing its fluid tight chamber from the main bodyportion bursts.

[0020] An inflation catheter which is attached to and in fluidcommunication with the fluid tight chambers of the graft via aninjection port disposed thereon, can be decoupled from the injectionport after completion of inflation by elevating pressure above apredetermined level. The elevated pressure causes a break in aconnection with the injection port by triggering a disconnect mechanism.Alternatively, the inflation catheter can be unscrewed from itsconnection. The injection port can include a check valve, seal or plugto close off the egress of inflation material once the inflationcatheter has been decoupled. The injection port could also be glued ortwisted to seal it off.

[0021] A graft having features of the invention may also be deployed bypercutaneous delivery with a catheter based system which has aninflatable balloon member disposed within expansion members of the graftin a collapsed state. The graft is percutaneously delivered to a desiredsite. Once the graft is axially positioned, the inflatable member of theballoon may be expanded and the expansion members forced radiallyagainst the interior surface of a body channel within which it isdisposed. The expansion members may also be self expanding from aconstrained configuration once the constraint is removed. After thegraft has been positioned by the catheter system, the inflatable cuff orcuffs and elongated channel or channels of the graft are pressurized.

[0022] These and other advantages of the invention will become moreapparent from the following detailed description of the invention whentaken in conjunction with the accompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 shows a perspective view of an endovascular graft havingfeatures of the invention.

[0024]FIG. 2 shows a longitudinal cross sectional view of anendovascular graft having a monolithic structure.

[0025]FIG. 3 shows an enlarged view of the longitudinal cross sectionalview of the endovascular graft of FIG. 2.

[0026]FIG. 4 shows a longitudinal cross-sectional view of anendovascular graft having features of the invention.

[0027]FIG. 5 shows an enlarged view of a portion of the endovasculargraft shown in FIG. 4.

[0028]FIG. 6 is a perspective view of a bifurcated endovascular grafthaving features of the present invention.

[0029]FIG. 7 is a transverse cross-sectional view of a bifurcatedportion of an endovascular graft taken at 7-7 of FIG. 6.

[0030] FIGS. 8A-8C depict perspective views of a bifurcated endovasculargraft having features of the present invention in various stages ofdeployment.

[0031]FIG. 9A is an enlarged longitudinal cross sectional view of thevalve that could be used to maintain inflation of a fluid tight chamberin the endovascular graft taken at 9-9 of FIG. 8A.

[0032]FIG. 9B is an enlarged longitudinal cross sectional view of analternative seal that could be used to maintain inflation of a fluidtight chamber in the endovascular graft taken at 9-9 of FIG. 8A.

[0033]FIG. 9C is an enlarged longitudinal cross sectional view of analternative sealing plug that could be used to maintain inflation of afluid tight chamber in the endovascular graft taken at 9-9 of FIG. 8A.

[0034]FIG. 10 is an enlarged longitudinal cross sectional view of arupture disc that could be used to control the inflation sequence of aninflatable endovascular graft taken at 10-10 of FIG. 8C.

[0035]FIG. 11 is a plot of inflation pressure of an inflatableendovascular graft with respect to time for an endovascular graft havingfeatures of the present invention including rupture discs which areconfigured to yield at various predetermined pressures.

DETAILED DESCRIPTION OF THE INVENTION

[0036]FIG. 1 shows a perspective view of an endovascular graft 10 havingfeatures of the present invention and having a proximal end 11 and adistal end 12. The graft is supported by an inflatable frame 13 whichhas a proximal end 14 and a distal end 15 and is shown in its deployedstate. The inflatable frame structure 13 has a proximal inflatable cuff16 at the proximal end 14 and an optional distal inflatable cuff 17 atthe distal end 15. The inflatable cuffs 16 and 17 can be annular inshape when deployed, although the cuffs can conform to the shape of thevessel within which they are deployed, and can have an outside diameteror cross sectional dimension of about 10 to about 45 mm, preferablyabout 16 to about 28 mm. There is at least one elongated inflatablechannel 18 disposed between the proximal inflatable cuff 16 and thedistal inflatable cuff 17. The inflatable frame 13 can be from about 5to about 30 cm in length, preferably about 10 to about 20 cm in length.Disposed between the proximal inflatable cuff 16, the distal inflatablecuff 17 and the elongated inflatable channel 18 is a thin flexible layer21 that forms a longitudinal lumen 22 which can confine a flow of fluidtherethrough. The thin flexible layer 21 may be made from the samematerial as the inflatable cuffs 16 and 17 and elongated channel 18 andbe integral with the construction of those elements forming a monolithicstructure. The thin flexible layer 21 and the materials used to form theframe structure 13 can have a wall thickness of about 0.1 to about 0.5mm, preferably about 0.15 to about 0.25 mm. The inflatable frame 13 maybe constructed from any suitable medical polymer or other material,including flouropolymers, PVCs, polyurethanes, PET, ePTFE and the like.Preferably the inflatable frame 13 and thin flexible layer 21 are madefrom ePTFE. A proximal neck portion 23 is attached to the proximal endof the inflatable frame structure 13 and serves as an additional meansto seal the graft against the inside of a body passageway, provides ameans of biasing a proximal end of the graft 11, and provides a smoothflow transition into longitudinal lumen 22.

[0037] An expansion member 24 having a proximal end 25 and a distal end26 has the distal end secured to the proximal end 14 of the frame 13.The distal end 26 of the expansion member may also be secured to theproximal neck portion 23. The expansion member 24 can be made fromexpandable rings 27 formed in a zig-zag pattern and connected by links28. The expansion member 24 is preferably a self-expanding member thatexpands to contact the inside wall of a body passage upon release from aconstrained state. The expansion member 24 may be made from any suitablematerial that permits expansion from a constrained state, preferably ashape memory alloy such as Nitinol. The expansion member 24 may beconfigured to self expand from a constrained state or be configured toexpand as a result of an outward radial force applied from within. Othermaterials suitable for construction of the expansion member 24 includestainless steel, MP35N alloy, shape memory alloys other than Nitinol,fiber composites and the like. The links 28 allow articulation of theexpansion member 24 to traverse curvature of a patient's anatomy bothduring delivery and in situ. The expansion member 24 has a generallycylindrical shape but may also have outwardly directed protuberances 32that are designed to engage the inside surface of a body passage. Theexpansion member 24 is generally cylindrical in shape when deployed,although the expansion member can conform to the shape of the vesselwithin which it is deployed, and can have a length of about 0.5 to about5 cm, preferably about 1 to about 4 cm. The diameter of the expansionmember 24 is typically similar to that of the inflatable cuffs 16 and17, and can be about 10 to about 35 mm, preferably about 16 to about 28mm. The high strength material from which the expansion member 24 ismade can have a cross sectional dimension of about 0.1 to about 1.5 mm,preferably about 0.25 to about 1 mm.

[0038] The graft 10 is generally deployed by inflation of the inflatableframe structure 13 with a pressurized material of solid particles, gas,fluid or gel which can be injected through an injection port 33. Thepressurized material may contain a contrast medium which facilitatesimaging of the device while being deployed within a patient's body. Forexample, radiopaque materials such as bismuth, barium, gold, platinum,tantalum or the like may be used in particulate or powder form tofacilitate visualization of the graft under fluoroscopy. Fixedradiopaque markers may also be attached or integrally molded into thegraft for the same purpose, and may be made from the same radiopaquematerials discussed above.

[0039]FIG. 2 shows a longitudinal cross sectional view of theendovascular graft shown in FIG. 1. Within the proximal inflatable cuff16 is a fluid tight chamber 41 which is in fluid communication with afluid tight chamber 42 of the elongated inflatable channel 18. The fluidtight chamber 42 of the elongated inflatable channel is in fluidcommunication with a fluid tight chamber 43 within the optional distalinflatable cuff 17. A longitudinal axis 44 of the graft 10 is shown inaddition to a proximal inlet axis 45 which forms an inlet axis angle 46with the longitudinal axis. The angled inlet axis 45 is generallycreated by the proximal neck portion 23 and provides the graft with aprofile which can conform to the morphology of a patient's vasculature.The expansion member 24 has a longitudinal axis 47 which is generallycoextensive with the proximal inlet axis 45, but can further bend toconform to local anatomy including neck angulation of a diseased vessel.

[0040]FIG. 3 shows an enlarged view of the longitudinal cross sectionalview of a portion of the proximal end 11 of the graft 10 shown in FIG.2. A more detailed view of the fluid tight chamber 41 of the proximalinflatable cuff 16 can be seen as well as a more detailed view of theattachment of the distal end 26 of the expansion member 24 to theproximal neck portion 23. The thin flexible layer 21 can be seendisposed between the proximal inflatable cuff 16 and the elongatedinflatable channel 18. The expandable rings 27 of the expansion member24 are connected by links 28 which can be made from the same material asthe expansion member or any other suitable material such as abiocompatible fiber or a metal such as stainless steel or Nitinol.

[0041]FIG. 4 is a transverse cross-sectional view of an embodiment of anendovascular graft 51, having features of the invention. The proximalinflatable cuff 52, distal inflatable cuff 53, and elongated inflatablechannel 54 are formed by sealingly bonding strips of material 55 over atubular structure 56. The strips 55 are bonded at the edges 57 so as toform fluid tight chambers 58 therein. If the material of the strips 55which have been bonded to the tubular structure 56 are of a permeablecharacter, an additional material may be used to coat the inside of thefluid tight chambers in order to make them impermeable to fluids.Alternatively, the material of the strips 55 and the material of theelongated tubular member 56 adjacent thereto may be made impermeable byundergoing further thermal, mechanical, or chemical processing.Preferably, thermo-mechanical compaction would be used to render thefluid tight chambers 58 impermeable to fluids which would be suitablefor inflating the graft 51.

[0042] The proximal end 61 of the graft 51 has a proximal neck portion62 which has an inlet axis 63 which forms an inlet axis angle 64 with alongitudinal axis 65 of the graft. The inlet axis angle 64 allows thegraft 51 to better conform to a morphology of a patient's vascularchannels. An expansion member 66 is also located at the proximal end 61of the graft 51 and is formed of expandable rings 67 held together bylinks 68. The expansion member 66 has a longitudinal axis 71 which cancoincide with the inlet axis 63 of the proximal neck portion 62. Thegraft 51 has a thin flexible layer 72 which extends from the distal end73 of the graft 51, to the proximal end of the graft 61, including theproximal neck portion 62. The thin flexible layer 72 forms alongitudinal lumen or channel 74 upon deployment of the graft, whichconfines a flow of blood or other bodily fluid therethrough.

[0043]FIG. 5 is an enlarged view of the longitudinal cross-sectionalview of the endovascular graft of FIG. 4. A more detailed view of thefluid tight chamber 58 of the proximal inflatable cuff and elongatedinflatable channel can be seen. The edges of the strips 57 which formthe proximal inflatable cuff 52 and the elongated inflatable channel 54are bonded at the edges by any suitable technique such as the use ofadhesives, solvents, or heat. Suitable adhesives would include epoxiesand cyanoacrylates or the like. Materials suitable for use as the thinflexible layer 72 or the strips 55 includes Dacron, Nylon, Teflon, andalso such materials as PVC, polyethylene, polyurethane and ePTFE.

[0044]FIGS. 6 and 7 depict an endovascular graft 81 having features ofthe invention which has a first bifurcated portion 82 and a secondbifurcated portion 83. A main body portion 84 of the graft 81 has aproximal end 85 and a distal end 86 with a proximal neck portion 87disposed at the proximal end as well as an expansion member 91 which canbe formed of expandable rings 92 of a suitable material which have beenlinked together. At the distal end 86 of the main body portion 84 thereis an optional distal inflatable cuff 93 which is connected fluidly to aproximal inflatable cuff 94 by an elongated inflatable channel 95. Thedistal inflatable cuff 93 may optionally be replaced by a manifold orother suitable structure for fluid connection between the elongatedinflatable channel 95 and the first bifurcated portion 82 or the secondbifurcated portion 83.

[0045] The first bifurcated portion 82 has a proximal end 96 and adistal end 97 with an optional distal inflatable cuff 98 located at thedistal end. The distal end of the first bifurcated portion 97 may havean expansion member in conjunction with or in place of the distalinflatable cuff 98. The proximal end 96 of the first bifurcated portion82 is attached to the distal end 86 of the main body portion 84 of thegraft 81. The first bifurcated portion 82 has an optional inflatableelongated channel 101 which fluidly connects the distal inflatable cuff98 of the first bifurcated portion 82 with the distal inflatable cuff 93of the main body portion 84. The inflatable elongated channel 101 alsoprovides support for first bifurcated portion 82.

[0046] The second bifurcated portion 83 generally has a structuresimilar to that of the first bifurcated portion 82, with a proximal end102 and a distal end 103. The distal end 103 has an optional distalinflatable cuff 104. The proximal end 102 of the second bifurcatedportion 83 is connected to the distal end 86 of the main body portion 84of the graft 81. The distal end of the second bifurcated portion 103 mayhave an expansion member in conjunction with or in place of the distalinflatable cuff 104. The second bifurcated portion 83 has an optionalinflatable elongated channel 105 which fluidly connects the distalinflatable cuff 104 of the second bifurcated portion 83 with the distalinflatable cuff 93 of the main body portion 84. The inflatable elongatedchannel 105 also provides support for the second bifurcated portion 83.The inflatable elongated channel of the first bifurcated portion 101 andinflatable elongated channel of the second bifurcated portion 105 mayhave a linear configuration as shown, a helical configuration similar tothe main body portion 84, or any other suitable configuration. Disposedbetween the proximal inflatable cuff 94, distal inflatable cuff 93 andelongated inflatable channel 95 of the main body portion 84 of the graft81 is a thin flexible layer 106 which forms a longitudinal lumen 107 toconfine the flow of blood or other bodily fluid therethrough. Disposedbetween the distal inflatable cuff 98 and the elongated inflatablechannel 101 of the first bifurcated portion 82 and the distal inflatablecuff 93 of the main body portion 84 is a first thin flexible layer 108which forms a longitudinal lumen 109 which is in fluid communicationwith the longitudinal lumen 107 of the main body portion 84. The secondbifurcated portion may also be formed separate of a main body portionand be joined to the main body portion after percutaneous deliverythereof by docking methods. The first and second bifurcated portions 82and 83 are generally cylindrical in shape when deployed, although theycan conform to the shape of a vessel within which they are deployed, andcan have a length from about 1 to about 10 cm. The outside diameter ofthe distal ends of the first and second bifurcated portions 82 and 83can be from about 2 to about 30 mm, preferably about 5 to about 20 mm.

[0047] A second thin flexible layer 111 is disposed between the distalinflatable cuff 104 and elongated inflatable channel 105 of the secondbifurcated portion 83 and the distal inflatable cuff 93 of the main bodyportion 84. The second thin flexible layer 111 forms a longitudinallumen 112 which is in fluid communication with the longitudinal lumen107 of the main body portion 84. The thin flexible layer of the firstbifurcated portion surrounds the elongated lumen of the first bifurcatedportion. The thin flexible layer of the second bifurcated portionsurrounds the elongated lumen of the second bifurcated portion.

[0048] FIGS. 8A-8C depict an embodiment of an endovascular graft 121having features of the invention in various stages of deployment. InFIG. 8A, an inflation catheter 122 is connected to an injection port 123in a first bifurcated portion 124 of the endovascular graft 121. Theinjection port 123 is connected to a distal inflatable cuff 125 of thefirst bifurcated portion 124 and is in fluid communication with a fluidtight chamber 126 therein. The first bifurcated portion 124 and a mainbody portion 127 have been substantially inflated in FIG. 8A, however, asecond bifurcated portion 128 has been prevented from deployment byrupture discs 131 which have been disposed within fluid tight chambers132 of the elongated inflatable channels 133 of the main body portion127 which are connected to fluid tight chambers 134 of elongatedinflatable channels 135 of the second bifurcated portion 128. In FIG.8B, the second bifurcated portion 128 has been substantially deployedsubsequent to a rupture or bursting of the rupture discs 131 disposedwithin the fluid tight chambers 132 and 134 of the elongated inflatablechannels 133 and 135 which permitted the flow of a pressurized substancetherein. FIG. 8C shows the endovascular graft fully deployed andillustrates detachment of a distal end 136 of the inflation catheter 122from the injection port 123 which is carried out by increasing thepressure within the inflation catheter until a disconnect mechanism 137is triggered.

[0049]FIG. 9A illustrates a longitudinal cross-sectional view taken at9-9 of FIG. 8A. The one-way inflation valve 141 has an outer wall 142,an inner lumen 143, an annular spring stop 144, an annular ball seal145, a sealing body 146 and a sealing spring 147. The configurationdepicted in FIG. 9A allows for the ingress of an inflation medium in thedirection of the arrow 148 while preventing an egress of same oncepressure is removed.

[0050]FIG. 9B illustrates an alternative one way valve. The one-wayinflation valve 149 has an outer wall 149A, an inner lumen 149B, a firstreed valve 149C, and a second reed valve 149D which is fluidly sealedwith the first reed valve in a relaxed state. The configuration depictedin FIG. 9B allows for the ingress of an inflation medium in thedirection of the arrow 149E while preventing an egress of same oncepressure is removed.

[0051]FIG. 9C illustrates an alternative seal 150. The seal has an outerwall 150A, an inner lumen 150B, a plug 150C and a sealing surface 150D.The plug 150C has a sealing head 150E which sealingly engages thesealing surface 150D by irreversible deployment by application of forceto the plug in the direction of the arrow 150F.

[0052]FIG. 10 depicts a longitudinal cross-sectional view of a rupturedisc 151 taken at 10-10 of FIG. 8C. The rupture disc 151 has a wallmember 152 which is sealingly secured to the inside surface 153 of afluid tight chamber 154. The wall member 152 is configured to fail underpressure prior to the failure of the surrounding wall 155 of the fluidtight chamber 154 under pressure. The rupture disc 151 allows fordeployment and inflation of fluid tight chambers other than those whichhave been sealed by the rupture disc. Once sufficient force or pressureis exerted against the wall 152 of the rupture disc to cause failure,the rupture disc 151 will burst and permit the ingress of an inflationmedium and deployment of a portion of an inflatable graft, previouslysealed by the rupture disc.

[0053]FIG. 11 depicts a graphical representation of inflation pressure161 versus the time 162 at an injection port of an inflatable graft asdepicted in FIGS. 8A-8C during the deployment process. P₁ represents theinflation pressure at the injection port prior to the rupturing of anyrupture discs in the endovascular graft. P₂ represents the pressurerequired to cause failure or bursting of the weakest rupture disc in theendovascular graft after which a portion of the endovascular graftpreviously sealed by the weakest rupture disc is inflated and deployed.The pressure then increases over time to P₃ which is the pressure levelrequired to cause failure or bursting of a second rupture disc. P₄ isthe pressure level required for triggering a disconnect mechanism at thedistal end of the inflation catheter.

[0054] While particular forms of the invention have been illustrated anddescribed, it will be apparent that various modifications can be madewithout departing from the spirit and scope of the invention.Accordingly, it is not intended that the invention be limited, except asby the appended claims.

What is claimed is:
 1. An endovascular graft for placement in apatient's body channel, comprising: a) a flexible tubular structurehaving a proximal end portion which comprises an inflatable cuff; and b)an expansion member coupled to the flexible tubular structure, disposedproximal of the inflatable cuff and configured to expand in an outwardradial direction to mechanically anchor to the patient's body channel.2. The endovascular graft of claim 1 wherein the flexible tubularstructure comprises a porous polymer.
 3. The endovascular graft of claim2 wherein the porous polymer comprises ePTFE.
 4. The endovascular graftof claim 1 wherein the expansion member comprises a stent.
 5. Theendovascular graft of claim 4 wherein the stent comprises a shape memoryalloy.
 6. The endovascular graft of claim 1 wherein the expansion memberfurther comprises barbs extending at least partially in an outwardradial direction and configured to penetrate tissue of the patient'sbody channel.